1. Field of the Invention
The present invention relates generally to the field of diagnostic tests and, more particularly, to a precursor indicator composition for detecting an analyte.
2. Description of the Prior Art
The prior art has developed a wide variety of test compositions for the determination of specific constituents in liquids such as urine and blood. These have taken a variety of forms, one of the most popular being reagent impregnated test strips of the dip-and-read type, certain of which are useful for the determination of such constituents as glucose, protein, occult blood, and the like in body fluids, whereas others are useful for the determination of various constituents in other liquids, such as swimming pool water, cutting fluids, and the like.
Many current methods require the use of numerous labile ingredients. At present one of the greatest difficulties faced by diagnostic reagent manufacturers is the stability and shelf life of their product. Unreliable tests can result in the withholding of critical medical treatment, unnecessary treatment and lost income to the patient and the manufacturer. As a result many varied attempts have been made at overcoming this problem.
Compositions and test devices in the form of treated carrier matrices are often stored for considerable periods of time before use, and it is therefore desirable that the reagents chosen are not easily auto-oxidizable in air. It has generally been considered necessary that the test devices be protected from exposure to light and often it has been necessary to keep them sealed in a moisture repellent package which is opened only for removal of one or more test devices shortly before use.
In another approach, various stabilizer compounds have been added to analytical compositions. Exemplary of efforts in this approach are U.S. Pat. Nos. 3,551,296; 3,950,133; 4,118,279; and 4,132,598.
In the variety of approaches taken to enhance the stability of diagnostic compositions it has heretofore been considered necessary to add stabilizer compounds, which present the possibility of altering the reaction characteristics of the composition, or accepting that the composition is labile and providing otherwise unnecessary elaborate packaging to protect the composition.
It is therefore an object of the present invention to provide an improved test for the detection of an analyte, particularly in body fluids.
It is yet another object of the invention to provide an improved test for an analyte using materials which provide improved stability.
A further object of the invention is to provide an improved test for the detection of an analyte which undergoes alteration to an analyte responsive form when put in use.